Cementing Solutions for Geothermal Wells

The solutions starts with the elimination of cement carbonationCarbon dioxide (CO2 ) is a common element in downhole fluids, whether naturally occurring in groundwaters or the result of CO2 injection processes. When CO2 comes into contact with the Portland cement that is used to cement well casings, it produces a deterioration phenomenon in the cement called carbonation. Over time, the loss of cement due to carbonation can cause serious damage to downhole tubulars and destroy zonal isolation integrity, resulting in costly remedial services or even abandonment of a well.

A CO2— resistant formulation from Halliburton resists CO2—and more
ThermaLock™ cement is a specially formulated calcium phosphate cement that is both CO2 and acid resistant. The result of a joint development project for high temperature, geothermal wells, ThermaLock cement is now being promoted as an alternative for Portland cement wherever CO2 may be encountered. It has been laboratory tested and proven at temperatures as low as 140°F and as high as 700°F.

Halliburton utilizes reverse cementing method when required to help achieve and retain a reliable annular seal for the life of geothermal wellsOur ThermaLock™ cement—a specially formulated calcium phosphate cement that resists cement degradation caused by CO2 exposure and ultra-high temperatures commonly found in geothermal environments—helps protect the casing by sealing it away from contact with corrosive fluids.

Reverse cementing overcomes a major pressure challenge
Conventional cementing methods involve pumping cement through the casing to come up the annulus. Reverse cementing involves pumping the slurry down the annulus directly and taking returns through the casing. This requires specially designed casing equipment and monitoring capabilities to determine the top of cement inside the casing. This method is used to lower bottom hole circulating pressure to avoid damaging or breaking down weak formations.

Wells that require the method of reverse cement benefit from:

Reduced equivalent circulating densities

Improved mud displacement

Shorter slurry thickening times

Improved compressive strength development

Improved safety and environmental management

Flexible cement slurry selection

Improved production due to less risk of cement invasion into the producing zone